Non-Newtonian fluids and more particularly, shear thickening fluids are being considered and investigated for potential commercial use as materials for liquid body armour or protective clothing due to their unique properties. The primary focus of the investigations have revolved around adaptive stiffness and dampening properties that can prevent ballistic weapons or sharp knives or stakes from penetrating a piece of body armour or protective clothing.
People may be exposed to noise pollution from their ambient environment (for example, from traffic, from construction sites, from aircraft, etc.). People may also be intentionally exposed to high sound levels (for example, from cell phones, MP3 players, home theater equipment, rock concerts, etc.). Studies have shown that ear damage, which may lead to permanent hearing impairment, is not only increasing in the general population, but may be increasing at a significantly faster rate in younger populations. The potential for noise induced hearing loss (NIHL) may be a function of both a level and a duration of exposure to a sound stimulus. Studies have also indicated that hearing damage is a cumulative phenomenon. Although hearing damage due to industrial or background noise exposure is more thoroughly understood, there may also be a risk of hearing damage from the exposure to intentional excessive noise, such as with the use of headphones.
Devices which attenuate sound directly to the ear canal are known. Conventional devices typically fit in the ear, around the ear and/or beyond the ear. Examples of these devices include headphones, headsets, earbuds and hearing aids. Earpieces that occlude the ear canal may provide increased attenuation of the ambient environment, offering improved sound isolation. However, conventional in-ear, in-concha or in canal earpieces may be fitted for a cross-section of a population and may not provide adequate sound isolation. Conventional in-ear, in-concha or in canal earpieces, thus, may not be properly fitted to the individual user and may not be adequately sealed, leading to reduced sound attenuation of the ambient environment. Furthermore, even if property fitted, as the ambient environment becomes louder, the effectiveness of the existing materials used for sound attenuating or isolation in-ear earpiece (or other devices fitting outside the ear) may not provide adequate protection. Most often, they are static in their attenuation properties, whereby the maximum attenuation is provided regardless of the ambient sound level.